Telemetrically controlled band for regulating functioning of a body organ or duct, and methods of making, implantation and use

ABSTRACT

Apparatus and methods are provided comprising an implantable non-hydraulic ring that encircles and provides a controllable degree of constriction to an organ or duct and an external control that powers and controls operation of the ring. The ring includes a rigid dorsal periphery that maintains a constant exterior diameter, and a compliant constriction system that reduces intolerance phenomena. A high precision, energy efficient mechanical actuator is employed that is telemetrically powered and controlled, and maintains the ring at a selected diameter when the device is unpowered, even for extended periods. The actuator provides a reversible degree of constriction of the organ or duct, which is readily ascertainable without the need for radiographic imaging. Methods of use and implantation also are provided.

FIELD OF THE INVENTION

This invention relates to laparoscopic implants designed to be implantedin the body of a patient around a biological organ having a pouch orduct to regulate functioning of the organ or duct. More specifically,the present invention is directed to an implantabletelemetrically-powered and controlled ring suitable for use as a gastricband to treat obesity or as an artificial sphincter.

BACKGROUND OF THE INVENTION

Obesity refers to a body weight that exceeds the body's skeletal andphysical standards. One well recognized parameter used to measureobesity is not directly the weight but the Body Mass Index (BMI) becauseit takes into account patient height: BMI is calculated by dividingweight by height squared and is expressed in kg/m2.

Obesity is usually defined as a BMI of 30 kg/m2 or greater, and isfurther broken down into Class I (BMI of 30-34.9 kg/m2), Class II (BMIof 35-39.9 kg/m2) also called severe obesity, and Class III (BMI of 40kg/m2 or greater), also called extreme obesity. Obesity is considered“morbid” when the BMI is over 40 (extreme obesity) or the BMI is over 35(severe obesity) and serious comorbidities are present.

Obesity is well recognized as a serious health problem, and isassociated with numerous health complications, ranging from non-fatalconditions to life threatening chronic diseases. According to the WorldHealth Organization, the non-fatal, but debilitating health problemsassociated with obesity include respiratory difficulties, chronicmusculoskeletal problems, skin problems and infertility.Life-threatening problems fall into four main areas: cardiovasculardisease problems; conditions associated with insulin resistance such astype 2 diabetes; certain types of cancers, especially the hormonallyrelated and large bowel cancers; and gallbladder disease. Beyond thesephysiological problems, obesity has also psychological consequences,ranging from lowered self-esteem to clinical depression.

Surgical intervention generally is the treatment of choice for patientsafflicted with morbid obesity. Such intervention not only mitigates themyriad health problems arising from overweight, but may reduce the riskof early death of the patient. Left untreated, morbid obesity may reducea patient's life expectancy by ten to fifteen years.

Morbidly obese patients as a group are poorly adapted to attainsustainable long-term weight loss using non-surgical approaches, such asstrict diets combined with exercise and behavioral modification, eventhough such methods are acknowledged to be the safest. For this reason,there is a continuing need for direct intervention to provide effective,long-term treatments for morbid obesity.

Three main surgical procedures are currently in use: Roux-en-Y GastricBypass (“RYGB”), Vertical Banded Gastroplasty (“VBG”) and AdjustableGastric Banding (“AGB”).

In RYGB a small stomach pouch is created and a Y-shaped section of thesmall intestine is attached to the pouch so that food bypasses the lowerstomach, the duodenum and the first portion of the jejunum. The RYGBprocedure is both restrictive, in that the small pouch limits foodintake and malabsorptive, in that the bypass reduces the amount ofcalories and nutrients the body absorbs.

VBG employs a non-adjustable synthetic band and staples to create asmall stomach pouch. AGB employs a constricting synthetic ring that isplaced around the upper end of the stomach to create an artificial stomawithin the stomach. The band is filled with saline solution and isconnected to small reservoir/access-port located under the skin of theabdomen. The AGB band may be inflated, thereby reducing the size of thestoma, or deflated, thus enlarging the stoma, by puncturing theaccess-port with a needle and adding or removing saline solution. BothVBG and AGB are purely restrictive procedures, and have no malabsorptiveeffect.

An example of the AGB technique is described, for example, in U.S. Pat.No. 5,074,868 to Kuzmak. As described in that patent, a flexible band ofelastomeric material is implanted around the stomach to form a closedloop defining a fixed pre-established diameter. The body of the flexibleband includes an expandable chamber, which is linked via a tube to asubcutaneous injection port. Fluid may be introduced into the injectionport using a syringe to add or remove fluid from the expandable chamberand thus vary the internal diameter of the band and the diameter of thestoma. In this way, expansion of the chamber, in combination with thepre-established and fixed diameter of the band, permits adjustment ofthe stoma diameter and thus regulation of the quantity of food ingested.

While the device described in the Kuzmak patent is capable of providingsatisfactory results, it nevertheless-suffers from a number ofdrawbacks. The injection port is the source of many of the problemsencountered with the hydraulic gastric bands, including infection,damage to the tube due to imprecise puncturing with the needle,discomfort to the patient created by the port and difficulty in locatingthe port (often necessitating the use of x-ray to determine the locationand orientation of the port).

In addition, although the injection port makes it possible to makelimited adjustments to the diameter of the ring without major surgicalintervention, installation of the band may be accompanied by intolerancephenomena, such as vomiting. This drawback may arise from variouscauses, including too great a reduction in the diameter of the stoma,ineffective action of the band due to too great a stoma diameter,obstruction, infection or local or general inflammation.

Accordingly, it sometimes is necessary to re-operate, either to relievethe patient or to adjust or change the previously-implanted band. Insuch cases, the previously-implanted band must be cut and either removedor replaced, during operations that are difficult to carry out,difficult for the patient to tolerate and costly.

U.S. Pat. No. 5,938,669 to Klaiber et al. addresses some of the issuesarising from use of an injection port, and describes a gastric band thatis adjusted using a remote control in a non-invasive manner. The deviceincludes a control box that is implanted in the body of the patient andcoupled to the gastric band. The control box includes a battery-operatedelectric pump and valve that are coupled between an expandable chamberand a fluid reservoir. The control box also contains a radiofrequencytransceiver and microprocessor, which are arranged to communicate withan external remote control to control operation of the pump to add orremove fluid from the reservoir to the expandable chamber, therebyselectively varying the diameter of the stoma opening. The externalremote control is operated by a physician.

The device described in Klaiber presents an interesting and beneficialdevelopment for patients, but still suffers from a number of drawbacks.Implantation of that system's fluid reservoir into the body of thepatient requires a delicate procedure, so as to avoid puncture andmaintain watertightness. Likewise, the introduction of a battery withinthe patient's body confers an undesirable degree of fragility upon thesystem. For example, further surgical intervention is required toreplace a depleted or leaking battery.

Several attempts to overcome drawbacks associated withhydraulically-actuated gastric bands, such as described in the Kuzmakand Klaiber patents, are known in the art. For example U.S. Pat. No.6,547,801 to Dargent et al. describes a surgically implantedgastroplasty system having a flexible tractile element that engages amotor-driven notched pulling member. The motor is powered and controlledby an inductive circuit, so that the diameter of the ring may only bechanged by operation of the external remote control.

Although the system described in the Dargent patent overcomes problemsassociated with injection ports used in previously-knownhydraulically-actuated bands and with systems requiring implantablebatteries, it too is expected to suffer from a number of drawbacks. Forexample, while Dargent states that the gearing of the pulling member issufficient to prevent the band from unwinding in the unpowered state,the pulling member configuration still may permit the tractile elementto “jump” or slip if the band is subjected to compression. Further, asshown in the drawings of that patent, when the band contracts, ripplesform in the interior surface of the band that may cause inflammation orabrasion of the stomach.

In addition, it has been observed that within a few weeks ofimplantation of a gastroplasty band, fibrous tissue tends to overgrowand encapsulate the band. It is expected that, as in Dargent, where theexterior of the diameter of the band contracts upon actuation of themotor, such fibrous tissue may interfere with proper functioning of thedevice. Finally, while the band described in Dargent is flexible, it hasno ability to stretch, for example, as may be needed to accommodateconvulsive motions of the stomach, e.g., during vomiting, andconsequently may lead to patient intolerance problems.

All of the foregoing surgical techniques involve major surgery and maygive rise to severe complications. Recent developments have focused onthe use of laparoscopic implantation of the gastric ring to minimizepatient discomfort and recuperation time.

For example, U.S. Pat. No. 5,226,429 to Kuzmak describes ahydraulically-controlled gastric band that is configured to be implantedusing laparoscopic techniques. The band is specially configured to beinserted through a laparoscopic cannula, and includes an injection portto control the degree of constriction imposed by the band. As previouslynoted, however, that band is expected to suffer from the same drawbacksas previously-known hydraulic gastric bands. In addition, that patentprovides no teaching or suggestion as to how non-hydraulicallycontrolled gastic bands could be configured for laparoscopicimplantation. For example, the patent provides no teaching that wouldenable a clinician to adapt the non-hydraulic device described inDargent for laparoscopic implantation.

In view of the foregoing, it would be desirable to provide apparatus andmethods for regulating functioning of a body organ or duct that provideshigh precision in a degree of constriction imposed upon the organ orduct, without the drawbacks associated with the use of previously-knowninjection ports.

It further would be desirable to provide apparatus and methods forregulating functioning of a body organ or duct that maintains a desiredlevel of constriction over an extended period using a gear-drivenarrangement that may be implanted laparoscopically.

It also would be desirable to provide apparatus and methods forregulating functioning of a body organ or duct that is capable ofaccommodating occasional convulsive motions of the organ or duct.

It further would be desirable to provide apparatus and methods forregulating functioning of a body organ or duct that is telemetricallypowered, so as to avoid the need for re-operation to replace or repair adefective or depleted energy source.

It still further would be desirable to provide apparatus and methods forregulating functioning of a body organ or duct that is telemetricallycontrolled, provides a high degree of safety, and reliably imposes areproducible degree of constriction.

It also would be desirable to provide apparatus and methods forregulating functioning of a body organ or duct that maintains a constantexterior diameter, and is not rendered inoperative by tissue ingrowth orfibrous tissue encapsulation.

It further would be desirable to provide apparatus and methods forregulating functioning of a body organ or duct that may benon-invasively, safely and easily adjusted by a physician, without theneed for radiographic imaging.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention toprovide apparatus and methods for regulating functioning of a body organor duct that provides high precision in a degree of constriction imposedupon the organ or duct, without the drawbacks associated with the use ofpreviously-known injection ports.

It is a further object of the present invention to provide apparatus andmethods for regulating functioning of a body organ or duct thatmaintains a desired level of constriction over an extended period usinga gear-driven arrangement that may be implanted laparoscopically.

It is another object of this invention to provide apparatus and methodsfor regulating functioning of a body organ or duct that is capable ofaccommodating occasional convulsive motions of the organ or duct.

It is a further object of the present invention to provide apparatus andmethods for regulating functioning of a body organ or duct that istelemetrically powered, so as to avoid the need for re-operation toreplace or repair a defective or depleted energy source.

It is still another object of this invention to provide apparatus andmethods for regulating functioning of a body organ or duct that istelemetrically controlled, provides a high degree of safety, andreliably imposes a reproducible degree of constriction.

It is yet another object of the present invention to provide apparatusand methods for regulating functioning of a body organ or duct thatmaintains a constant exterior diameter, and is not rendered inoperativeby tissue ingrowth or fibrous tissue encapsulation.

It also is an object of this invention to provide apparatus and methodsfor regulating functioning of a body organ or duct that may-benon-invasively, safely and easily adjusted by a physician, without theneed for radiographic imaging.

These and other objects of the present invention are accomplished byproviding apparatus and methods wherein a non-hydraulic ring andassociated implantable controller are laparoscopically implanted in thebody of a patient, so that the ring encircles and provides acontrollable degree of constriction to an organ or duct. The ringaccording to the present invention comprises a rigid dorsal peripheralportion that maintains a constant exterior diameter, and a springportion that facilitates laparoscopic implantation of the device andprovides a degree of compliance to permit convulsive motion of the organor duct, thereby reducing intolerance phenomena.

In accordance with the principles of the present invention, the ringincludes a high precision, energy efficient mechanical actuator thatmaintains the ring at a selected diameter, when the device is unpowered,for extended durations. The implantable controller is telemetricallypowered and controlled, thereby eliminating the need for re-operation torepair or replace a defective or depleted energy source.

In a preferred embodiment, the ring includes a high precision motor thatimposes a reversible degree of constriction of the organ or duct byactuation of the motor, wherein the degree of constriction is readilyascertainable without the need for radiographic imaging. The ringfurther comprises a flexible element having a predefined screw threadpitch that provides a high degree of precision, while retaining goodflexibility. A contact is provided at the free end of the flexibleelement that mates with an electrical switch to establish a referenceposition for the ring in the fully opened position.

In addition, the ring comprises a soft and flexible ePTFE component,encapsulated in a leak-proof flexible membrane, that maintains a smoothcontact surface with the organ or duct, thereby permitting the ring toundergo considerable diametral contraction without inducing ripples orbunching in the underlying organ or duct.

The ring of the present invention includes a non-invasive, simple to useexternal control that may be operated by the physician, and which may beadjusted during an in-office procedure without the need for radiographicconfirmation. In addition, the ring and implantable controller areconfigured to be easily introduced through a commercially available 18mm trocar and implanted using conventional laparoscopic techniques.

Methods of implanting the apparatus of the present invention also areprovided.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects of the invention will be apparent uponconsideration of the following detailed description, taken inconjunction with the accompanying drawings, in which like referencecharacters refer to like parts throughout, and in which:

FIG. 1 is a perspective view of an exemplary ring system of the presentinvention including an external control and implantable ring;

FIGS. 2A and 2B are, respectively, a schematic diagram, partly incross-section, of the gastric band of FIG. 1 and a sectional view takenalong line 2B-2B of FIG. 2A;

FIGS. 3A and 3B are perspective views illustrating the degree ofconstriction attainable by the gastric band of the present inventionbetween the fully open and fully closed positions;

FIGS. 4A and 4B are cross-sectional views of the gastric band of thepresent invention along the lines 4A-4A and 4B-4B of FIGS. 3A and 3B,respectively;

FIG. 5 is a partial perspective view of a screw thread portion of thetension element of the present invention;

FIG. 6 is a perspective view of an entire tension element suitable foruse in the gastric band of the present invention;

FIG. 7 is a perspective view of the tension element of FIG. 6 coupled tothe rigid dorsal peripheral portion and motor housing of the gastricband;

FIG. 8 is a perspective view of the gastric band of FIG. 1 straightenedand inserted within a standard 18 mm trocar;

FIG. 9 is a cross-sectional view of an elastomeric housing of thegastric band depicting the path of the antennae wire and cavity thataccepts the tension element;

FIG. 10 is a perspective view of the actuator housing, tension elementand actuator of the present invention;

FIG. 11 is a perspective of the tension element engaged with theactuator;

FIG. 12 is a cross-sectional view depicting the construction of theactuator of FIG. 11;

FIG. 13 is a cross-sectional view depicting the construction of thereference position switch;

FIGS. 14A and 14B are perspective views illustrating the clip used toclose the gastric band into a loop;

FIG. 15 is a perspective view of the antennae/controller pod of thepresent invention;

FIG. 16 is a cut-away view of the interior of the implantableantenna/controller pod of FIG. 15;

FIG. 17 is a cross-sectional view of the antennae cable of FIG. 15;

FIG. 18 is a schematic view of the telemetric power and controlcircuitry of the present invention;

FIG. 19 is a detailed view of the signal strength indicator portion ofthe remote control of FIG. 1A;

FIG. 20 is a schematic diagram illustrating placement of the implantableportion apparatus of the present invention within a patient; and

FIGS. 21A-21H are views illustrating a method of laparoscopicallyimplanting the gastric band of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, the banding system of the present invention isdescribed, comprising external control 10 and implantable gastric band21. In the following description reference will be made, by way ofillustration, to a gastric band designed to be implanted around thestomach to selectively adjust the diameter of opening of the stoma, andthereby control food intake. Such regulation has the effect of creatinga feeling of satiety in the patient after relatively little food isconsumed, and provides an effective treatment for morbid obesity.

It is to be understood, however, that the present invention is in no waylimited to gastroplasty, but on the contrary, advantageously may beapplied to regulate the functioning of other body organs or ducts, suchas in the treatment of gastro-esophageal reflux disease, urinary orfecal incontinence, colostomy, ileostomy or to regulate blood flow inconnection with isolated organ perfusion for treatment of cancer. Fortreatment of urinary continence, the implantable portion of the systemwill be implanted around the bladder or urinary tract, while in the caseof fecal incontinence, the ring may be implanted around a portion of thegastro-intestinal tracts, such as anal structures of the intestine.

System Overview

With respect to FIG. 1, self-contained external control 10 compriseshousing 11 having control panel 12 and display screen 13. Externalcontrol 10 includes a digital signal processor and may bebattery-powered or powered using an external power supply, e.g.,connected to a wall socket. External antenna 14 is coupled to remotecontrol 10 via cable 15. As described more fully with respect to FIG.18, external control 10 includes a microprocessor that controls theemission of radiofrequency signals to the gastric band 10 to bothcontrol and power operation of the band.

External control 10 accepts patient microchip card 16, which correspondsto the specific gastric band implanted in the patient, and stores data,such as the implant identification number, adjustment parameters (e.g.,upper and lower limits of an adjustment range, etc.) and informationregarding the last adjustment position of the ring. External control 10includes signal strength indicator 17, as described hereinbelow withrespect to FIG. 19, ON/OFF button 18, OPEN button 19 a, CLOSE button 19b, COUPLING button 19 c and menu options panel 20.

During use of the device, the physician need only turn external control10 ON using button 18, position external antenna 14 over patient's chestabove antenna/controller pod 23, check the coupling by depressingCOUPLING button 19 c, and when the coupling is sufficient, adjust thedegree of constriction using OPEN button 19 a or CLOSE button 19 b. Thediameter of the band is continually displayed on display panel 13 with aprecision of about 0.1 mm for the entire range of diameters of the ring,e.g., from 19 mm fully closed to 29 mm fully opened.

Still referring to FIG. 1, gastric band 21 of the present invention nowis described, and includes ring 22 coupled to implantableantenna/controller pod 23 via cable 24. Pod 23 includes removable tag 25that may be used to laparoscopically position ring 22. Ring 21 includesfirst end 26 having clip 27 that slides over and positively engagessecond end 28 of the ring.

As described in detail below, ring 22 is configured to be straightenedto pass through the lumen of a commercially available 18 mm trocar fordelivery in a patient's abdomen. Tag 25, pod 23 and cable 24 then arepassed through clip 27 to form the ring into a substantially circularloop around an upper portion of the patient's stomach, thereby reducingthe diameter of the opening of the stomach. In its undeformed shape,ring 22 assumes a circular arc configuration that facilitatespositioning of the ring around the stomach and also in self-guiding theclipping procedure.

Ring 22 of the present invention comprises a flexible tubular bandhaving a smooth, flexible and elastic membrane, thus ensuring atraumaticcontact with the patient's stomach tissue that is easily tolerated. Whenengaged with dorsal element 38, membrane 39 is stretched by anappropriate factor (i.e., 20%-40%), so that when ring 22 is in its fullyclosed position, little or no wrinkling appears on the membrane surface.Ring 22 has approximately the shape of a torus of revolution ofsubstantially cylindrical cross-section. Alternatively, ring 22 may haveany other suitable cross-section, including rectangular. Housing 29 onsecond end 28, clip 27 on first end 26 and dorsal peripheral portion 30of ring 22 (indicated by the darker portions of ring 22 of FIG. 1),preferably comprise a biocompatible material such as silicone. Interiorportion 31 of ring 22 preferably comprises expandedpolytetrafluoroethylene (ePTFE), which permits longitudinal contractionwithout bunching or ripples, and is covered by a thin membrane ofprotective material, for example, based on or made of silicone.

Advantageously, as depicted in FIG. 1, portions of ring 22 employpolymeric components having different colors to facilitate laparoscopicmanipulation and implantation. In one preferred embodiment, interiorportion 31 of the ring comprises lighter colored materials while theclip 27 and housing 29 comprise darker colored materials, therebyindicating to the clinician which portions of ring 22 may be graspedduring implantation. In particular, the colors may consist of black,white and different shades of gray achievable with implantable silicone.

Implantable Ring

Referring now to FIGS. 2A and 2B, the internal structure of ring 22 isdescribed. In particular, as depicted in FIG. 2A, ring 22 includesflexible tension element 32 having fixed end 33 mounted to first end 26of the ring and free end 34 that is engaged with motor-driven actuator35 and extends into a cavity in housing 29. Tension element 32 isslidingly disposed within a substantially cylindrical tube ofcompressible material 36, e.g., ePTFE, as illustrated in FIG. 2B, sothat when tension element is pulled through actuator 35, compressiblematerial 36 is compressed and the diameter of opening 37 is reduced.Compressible material 36 preferably is surrounded on its dorsal facewith a flexible, but sturdier elastomeric material, such as siliconeelement 38. Both compressible material 36 and silicone element 38preferably are enclosed within a membrane of elastomeric biocompatiblematerial 39, as shown in FIG. 2B, to prevent tissue ingrowth between theePTFE tube and silicone element 38. Membrane 39 may be affixed to dorsalelement 38 using a biocompatible glue to prevent leakage in case ofaccidental puncture on the dorsal surface.

In accordance with one aspect of the present invention, ring 22 furthercomprises layer 40 of a relatively rigid material disposed on the dorsalperiphery of the ring. Layer 40, which may comprise a plastic or metalalloy, prevents the exterior diameter of ring 22 from changing duringadjustment of tension element to reduce internal diameter 37 of thering. Layer 40, by its structural rigidity, imposes a circular arc shapefor the entirety of ring 22. Advantageously, layer 40 allows the tensionelement to be adjusted following encapsulation of the gastric ring byfibrous tissue after implantation, since adjustment of internal diameter37 of the gastric ring does not change the external diameter of thering.

The foregoing feature is illustrated in FIGS. 3 and 4. In FIGS. 3A and3B, ring 22 is shown in its fully open and fully closed positions,respectively. As discussed above, layer 40 forms a rigid skeleton thatpermits the internal diameter of the ring to change while maintainingthe external diameter constant. Radial movement of tension element 32 istransmitted to membrane 39 by compressible material 36. ePFTE isparticularly well-suited for use as compressible material 36 because itcan undergo a 3:1 reduction in length without experiencing a significantincrease in cross-section.

Accordingly, as depicted in FIGS. 4A and 4B, increase or reduction ofthe length of tension element 32 results in reversible radialdisplacement at the internal periphery of the ring opposite the dorsalperiphery. This in turn translates into a variation of internal diameterD of the ring from a fully open diameter to a fully closed diameter.Preferably, the fully open diameter is about 35 mm, and the fully closeddiameter is about 15 mm. More preferably, the fully open diameter isabout 29 mm, and the fully closed diameter is about 19 mm.

Referring now to FIG. 5, tension element 32 is described. Tensionelement 32 preferably has sufficient flexibility to permit it to beformed into a substantially circular shape of the ring, while also beingable to transmit the force necessary to adjust the ring diameter.Tension element 32 therefore comprises flexible core 41, preferably ametal alloy wire of circular cross section, on which is fixed, and woundcoaxially, at least one un-joined coil spring which defines the screwthread pitch.

As shown in FIG. 5, tension element 32 preferably comprises twoun-joined coil springs that form a screw thread: first spring 42, woundhelicoidally along the flexible core 41, and second spring 43 of greaterexterior diameter. Second spring 43 preferably comprises coils 44 ofrectangular transverse section, so as to delineate a flat externalgeneratrix. First spring 42 is interposed between coils 44 of the secondspring 43 to define and maintain a substantially constant square screwthread pitch, even when the tension element is subjected to bending.

As a consequence of the foregoing arrangement, the ability of tensionelement 32 to maintain a substantially constant thread pitch, whensubjected to bending, confers great precision on adjustments of ring 22.This is especially so when it is realized that as the tension element isdrawn through actuator 35, an ever-increasing curvature is imposed onthe remaining portion of the tension element. However, because theforegoing arrangement of un-joined coils maintains a substantiallyconstant screw thread pitch, the energy needed to drive actuator 35remains low and the efficiency of energy transmission resulting from theuse of a square screw thread pitch remains high. In addition, the use ofa square screw thread pitch guarantees a stable adjustment position evenwhen the actuator is unpowered.

Second spring 43 advantageously may be made by laser cutting acylindrical hollow tube, e.g., made from stainless steel, oralternatively, by winding a wire with a rectangular, trapezoidal orother cross-section. When helically interwound with first spring 42,coils 44 of second spring 43 are naturally activated with an intrinsicelastic compression force from the adjacent coils of first spring 42. Aswill of course be appreciated, first spring 42 is fixedly joined toflexible core 41 at one end. At the second end, crimped cap 45 (see FIG.6) is located a short distance from the ends of springs 42 and 43 toallow for small extensions (to accommodate flexion of tension element32), but also to limit this extension to keep the thread pitchsubstantially constant.

Referring now to FIG. 6, the entirety of tension element 32 isdescribed. Free end 34 includes crimped cap 45, second spring 43 havingcoils with a square transverse section, and first spring 42 (not visiblein the figure, but intertwined between the coils of second spring 43).Flexible core 41 extends through first and second springs 42 and 43, andterminates close to cap 45. In accordance with one aspect of the presentinvention, tension element 32 further comprises third spring 46 that iscoupled to flexible core 41, and first and second springs 42 and 43 atjunction 47. Third spring 46 includes loop 48 at the end opposite tojunction 47, which permits the tension element to be mounted to firstend 26 of ring 22.

In accordance with the principles of the present invention, third spring46 is relatively stiff, but provides a needed degree of compliance tothe tension element. Whereas previously-known elastomeric bands providea small degree of compliance, previously-known non-hydraulic gastricbands, such as disclosed in the above-mentioned Dargent patent have nocompliance. Consequently, in the presence of vomiting, which is afrequent complication of gastric bands, previously-known gastric bandsprevent convulsive stomach motion, which may result in extremediscomfort to the patient. In the present invention, however, thirdspring 46 permits the gastric band to temporarily expand due toconvulsive activity, and afterwards return to the preselected internaldiameter. This feature is expected to significantly reduce patientdiscomfort and intolerance phenomena.

With respect to FIG. 7, tension element 32 is shown disposed withinskeleton 50 of the gastric ring 22. Skeleton 50 includes layer 51 thatforms the dorsal periphery (corresponding to layer 40 of FIGS. 2 and 4),anchor 52 that accepts loop 48 of tension element 32, and actuatorhousing 53. Skeleton preferably comprises a high strength moldableplastic. As further depicted in FIG. 7, skeleton 50 extends along agreater arc length than tension element 32. In accordance with anotheraspect of the present invention, third spring 46 permits gastric band 21to be straightened for insertion through a standard 18 mm trocar,despite the differential elongation of the skeleton and tension element.This feature'is illustrated in FIG. 8, which depicts ring 22 insertedthrough 18 mm trocar 55 so that the ring is substantially straight.

Referring now to FIG. 9, housing 29 of the free end of ring 22 isdescribed. Housing 29 comprises an elastomeric material, such assilicone, having recessed portion 56, tension element cavity 57 andcable lumen 58. Recess 56 is configured to accept actuator housing 53 ofskeleton 50, so that as tension element 32 is drawn through actuator 35it extends into tension element cavity 57. Cable lumen 58 extendsthrough housing 29 so that cable 24 may be coupled to actuator 35.Housing 29 preferably may be grasped in area G using atraumaticlaparoscopic graspers during manipulation of the device.

In FIG. 10, actuator housing 53 of skeleton 50 is shown with actuator 35and tension element 32 disposed therethrough. Antenna cable 24 iscoupled to motor (not shown) disposed within actuator housing 53.Tension element 32 is in the fully opened (largest diameter) position,so that crimped cap 45 contacts printed circuit board 59 of thereference position switch, described below with respect to FIG. 13.

Actuator

With respect to FIGS. 11 and 12, actuator 35 includes motor 66 coupledto antenna cable 24 that drives nut 60 through gears 61. Nut 60 issupported by upper and lower bearings 62 to minimize energy losses dueto friction. Nut 60 is self-centering, self-guiding and provides hightorque-to-axial force transfer. Moreover, nut 60 is expected to be morereliable than tangent screw arrangements employed in previously-knownmechanical gastric rings, and cannot jump or slip. In addition, nut 60is self-blocking, meaning that nut 60 will not rotate due to theapplication of pushing or pulling forces on tension element 32. Thiscondition may be achieved by ensuring that the height (h) of the threaddivided by the circumference of the screw (2πR) is less than thearctangent of the friction coefficient (μ):h/(2πR)<arctan(μ).

Gears 61 preferably are selected to provide good mechanical efficiency,preferably with a reduction factor greater than 1000. In addition, thevolume of the actuator depicted in FIGS. 11 and 12 may be quite small,with a total volume less than 1 cm³ and a diameter less than 12.5 mm, sothat the device may easily pass through a standard trocar. In apreferred embodiment, gears 61 are selected to provide a force of morethan 2 kg on the screw thread of the tension element at an electricalconsumption of only 50 mW. The gears and other components of actuator 35preferably are made of stainless steel or are gold plated to permitoperation in the high humidity likely to be encountered in a human body.

Motor 66 employed in actuator 35 preferably comprises a Lavet-type highprecision stepper motor with a flat magnetic circuit, such as are usedin watches. The motor preferably is a two phase (two coil) motor thatpermits bi-directional rotation, has good efficiency, and may besupplied with a square wave signal directly by the microcontrollercircuitry within antenna/controller pod 35, thus eliminating the needfor an interface circuit. Alternatively, the motor employed in actuator35 may be of a brushless DC type motor. In addition, the motorpreferably is compatible with magnetic resonance imaging, i.e., remainsfunctional when exposed to strong magnetic fields used in medicalimaging equipment.

Referring now to FIG. 13, the reference position switch of the presentinvention is described. Because the actuator of the present inventionemploys nut 60 driven by a stepper motor, there is no need for thesystem to include a position sensor or encoder to determine the lengthof tension element 32 drawn through the actuator. Instead, the diameterof ring 22 may be directly computed as a function of the screw threadpitch and the number of rotations of nut 60. To ensure an accuratecalculation of the degree of restriction imposed by the gastric ring,however, it is desirable to provide at least one reference point.

This reference datum is accomplished in the gastric ring of the presentinvention using a reference position switch that is activated when ring22 is moved to its fully open position. Crimped cap 45 on the free endof tension element 32 serves this function by contacting electricaltraces 63 on printed circuit board 59 (and also limits elongation of thescrew thread). Circuit board 59 is disposed just above bearing 65, whichforms part of actuator 35 (see also FIG. 10). When crimped cap 45contacts traces 63 it closes a switch that signals the implantablecontroller that the gastric ring is in the fully open position.

Ring Closure System

With respect to FIGS. 14A and 14B, a preferred embodiment of clip 27 forsecuring the gastric band in the closed position is described. Clip 27on first end 26 of the gastric ring includes aperture 70, tab 71 havinghinge 72 and slot 73. Aperture 70 is dimensioned to accept second end 28therethrough, while slot 73 is dimensioned to accept flange 74 disposedon second end 28.

To close ring 22, clip 27 is grasped by the tab 71 and tag 25 of pod 23(see FIG. 1) is inserted through aperture 70. Clip 27 is then pulledtowards second end 28 so that housing 29 passes through aperture 70while housing 29 is grasped with atraumatic forceps; the conical shapeof housing 29 facilitates this action. Force is applied to tab 71 untilslot 73 captures flange 74, thereby securing the gastric ring in theclosed position. The physician may subsequently choose to disengage slot73 from flange 74 by manipulating tab 71 using laparoscopic forceps, forexample, to reposition the ring. Advantageously, however, forcesinadvertently applied to tab 71 in an opposite direction will cause tab71 to buckle at hinge 72, but will not cause flange 74 to exit slot 73.Accordingly, hinge 72 of tab 71 prevents accidental opening of clip 70when the tab 71 is subjected to forces that cause the tab to foldbackwards away from body 29, such as may arise due to movement of thepatient, the organ, of or bolus of fluid passing through the organ.

Antenna/Controller Pod

With respect to FIGS. 15 and 16, antenna/controller pod 23 of thepresent invention is described. Pod 23 is disposed at the distal end ofcable 24 and includes removable tag 25 and holes 75. Tag 25 comprises agrip structure that facilitates manipulation and placement of the podduring implantation; after which the tag is removed using a scissorscut. Tag 25 also includes hole 25 b that allows the use of a suturethread to assist in passing the antenna/controller pod 23 behind thestomach. Holes 75 also are dimensioned to be compatible with standardsuture needles from size 1-0 to 7-0 to permit pod 23 to be sutured tothe patient's sternum, thereby ensuring that pod 23 remains accessibleto the external antenna and cannot migrate from a desired implantationsite.

As shown in FIG. 16, antenna/controller pod 23 encloses printed circuitboard 76 that carries the antenna and microcontroller circuitry ofgastric band 22. The antenna receives energy and commands from externalcontrol 10 (see FIG. 1), and supplies those signals to themicrocontroller, which in turn powers motor 66 of actuator 35. Thecircuitry of antenna/controller pod 23 uses the energy received from theincoming signal to power the circuit, interprets the commands receivedfrom external control 10, and supplies appropriate signals to the motorof actuator 35. The circuit also retrieves information regardingoperation of the motor of actuator 35 and relays that information toexternal control 10 via the antenna. The circuit board preferably iscovered with a water-resistant polymeric covering, e.g., Parylene, topermit use in the high (up to 100%) humidity environment encountered inthe body.

Antenna/controller pod 23 includes a mechanical closure system that isaugmented by silicone glue so that the pod is fluid tight. This siliconeglue also is used to protect soldered wires 79 from humidity. The podpreferably is small, e.g., 16 mm×33 mm×4 mm, to ensure compatibilitywith a standard 18 mm trocar and so as to be compatible with placementon the sternum. The pod preferably has a smooth, atraumatic shape toavoid tissue damage, has good mechanical strength to withstand handlingwith surgical graspers and to prevent mechanical deformation to theprinted circuit board, and has good electromagnetic permeability toallow efficient energy transmission through the pod. Antenna/controllerpod 23 preferably has a relatively thin planar configuration to avoidrotation of the pod when placed under the skin, and may include holesthat permit the pod to be sutured in position.

With respect to FIG. 17, antenna cable 24 is shown in cross-section.Cable 24 preferably is a coaxial shielded cable encapsulated in asilicone tube 77 to provide biocompatibility. Tube 77 is selected toprovide leak-proof encapsulation, with sufficient strength to permit thecable to be manipulated with atraumatic graspers. Braided shield 78 ofthe cable prevents longitudinal deformation of the cable, and surroundsfive helically wound insulated wires 79. Four of wires 79 are used tosupply power to the micromotor of actuator 35; the remaining wire andbraided shield 78 are used to supply a signal from the referenceposition switch to the controller.

As discussed above with respect to FIG. 1, the gastric band according tothe present invention provides an integrated system for regulating foodingestion in the stomach of a patient, wherein variation of the diameterof the gastric ring may be adjusted without any invasive surgicalintervention. To accomplish this, actuator 35 is linked to subcutaneousantenna/controller pod 23 to receive a radio frequency control and powersignal. In the preferred embodiment, the motor of the actuator has nointernal energy supply, but rather is powered by the receiving circuitof the antenna through a rechargeable energy storage device, such as acapacitor. In particular, the receiving circuit converts radio frequencywaves received from external control 10 via the antenna into a motorcontrol and power signal. In an alternative, although less preferred,embodiment the actuator may be driven via an implantable rechargeablebattery.

Power and Control Circuitry

Referring to FIG. 18, a presently preferred embodiment of the circuitryemployed in external control 10 and gastric band 22 of the presentinvention is described, based on the principle of passive telemetry byFM-AM absorption modulation. External control 10 is shown on the lefthand side of FIG. 18, and includes microprocessor 80 coupled to controlpanel 12 and display 13 (see FIG. 1). External control 10 produces asignal comprising one or more data bytes to be transmitted to theimplantable antenna/controller pod 23 and actuator 35 (shown on theright hand side of FIG. 18).

External control 10 includes modulator 81 for amplitude modulation ofthe RF wave from RF generator 82, which signal is emitted by theexternal antenna 14. The emitted wave is received by the antenna 83 inthe antenna/controller pod 23, where AM demodulator 84 extracts the databytes from the envelope of received RF signal. The data bytes then aredecoded and written into an EEPROM of microcontroller 85. A special codeis used that allows easy decoding of the data by microcontroller 85, butalso provides maximal security against communication failure.

External oscillator 86, which is a voltage controlled oscillator (VCO),provides a clock signal to microcontroller 85. Oscillator 86 may consistof, for example, a relaxation oscillator comprising an externalresistor-capacitor network connected to a discharging logic circuitryalready implemented in the microcontroller or a crystal oscillatorcomprising a resonant circuit with a crystal, capacitors and logiccircuits. The former solution requires only two additional components,is suitable when the stability of the frequency is not critical, and haslow current consumption; the latter solution provides a more stablefrequency, but requires a greater number of additional components andconsumes more power. Oscillator 86 preferably comprises the external RCnetwork, due to its simplicity.

Microcontroller 86 interprets the received instructions and produces anoutput that drives the motor of actuator 35. As discussed above,actuator 35 comprises a bi-directional stepper motor that drives nut 60through a series of reducing gears. Preferably, the two coils of thestepper motor of actuator 35 are directly connected to microcontroller85, which receives the working instructions from demodulator 84,interprets them and provides the voltage sequences to the motor coils.When the supply of voltage pulses to the stepper motor stops, the gearsare designed to remain stationary, even if a reverse torque or force isapplied to nut 60 by tension element 32.

As also described above, use of a stepper motor in actuator 35 makes itis possible to obtain positional information on nut 60 and tensionelement 32 without the use of sensors or encoders, because thedisplacement of the tension element is proportional to the number ofpulses supplied to the stepper motor coils. Two signals are employed toensure precise control, reference position signal S_(RP), generated bythe reference position switch of FIG. 13, and the actuator signal S_(A).

According to one preferred embodiment, signal S_(A) is the voltagesignal taken at one of the outputs of microcontroller 85 that isconnected to the motor coils of actuator 35. Alternatively, signal S_(A)could be derived from the current applied to a motor coil instead of thevoltage, or may be an induced voltage on a secondary coil wrapped aroundone of the motor coils of actuator 35. In either case, signal S_(A) is apulsating signal that contains information on the number of steps turnedby the rotor and further indicates whether blockage of the mechanism hasoccurred. Specifically, if the rotor of the stepper motor fails to turn,the magnetic circuit is disturbed, and by induction, affects signalS_(A), e.g., by altering the shape of the signal. This disturbance canbe detected in the external control, as described below.

Signals S_(A) and S_(RP) are converted into frequencies using externaloscillator 14, so that the voltage level of signal S_(A) applied toexternal oscillator 86 causes the oscillator to vary its frequencyF_(osc) proportionally to the signal S_(A). Thus, F_(osc) contains allthe information of signal S_(A). When crimped cap 45 and tension element32 are in the reference position (gastric ring 22 is fully open), thereference position switch produces reference position signal S_(RP).Signal S_(RP) is used to induce a constant shift of the frequencyF_(osc), which shift is easily distinguishable from the variations dueto signal S_(A). If oscillator 86 is a relaxation oscillator, asdescribed above, signals S_(A) and S_(RP) modify the charging current ofthe external resistor capacitor network. In this case, the relaxationoscillator preferably comprises an external resistor-capacitor networkconnected to a transistor and a logic circuit implemented inmicrocontroller 85. With S_(A) and S_(RP), the goal is to modify thecharging current of the capacitor of the RC network to change thefrequency of the relaxation oscillator. If the charging current is low,the voltage of the capacitor increases slowly and when the threshold ofthe transistor is reached, the capacitor discharges through thetransistor. The frequency of the charging-discharging sequence dependson the charging current.

If oscillator 86 is a crystal oscillator, signals S_(A) and S_(RP)modify the capacitor of the resonant circuit. In this case, the crystaloscillator circuit preferably comprises a crystal in parallel withcapacitors, so that the crystal and capacitors form a resonant circuitwhich oscillates at a fixed frequency. This frequency can be adjusted bychanging the capacitors. If one of these capacitors is a Varicap (a kindof diode), it is possible to vary its capacitance value by modifying thereverse voltage applied on it, S_(A) and S_(RP) can be used to modifythis voltage.

In either of the foregoing cases, signals S_(A) and S_(RP) are used tomodify at least one parameter of a resistor-capacitor (RC) networkassociated with the oscillator 14 or at least one parameter of a crystaloscillator comprising the oscillator 14.

Referring still to FIG. 18, signals S_(A) and S_(RP), derived from thestepper motor or from the output of the microcontroller 85, may be useddirectly for frequency modulation by the oscillator 86 without anyencoding or intervention by the microcontroller 85. By using oscillator86 of microcontroller 85 as part of the VCO for the feedback signal, noadditional components are required, and operation of micro controller 85is not adversely affected by the changes in the oscillator frequencyF_(osc). The oscillating signal F_(osc) drives voltage driven switch 87for absorption modulation, such that feedback transmission is performedwith passive telemetry by FM-AM absorption modulation.

More specifically, signal F_(osc) drives switch 87 such that during theON state of the switch 87 there is an increase in energy absorption byRF-DC converter 88. Accordingly, therefore the absorption rate ismodulated at the frequency F_(osc) and thus the frequency of theamplitude modulation of the reflected wave detected by external control10 contains the information for signal S_(A). As discussed below, pickup90 in external control 10 separates the reflected wave where it can bedecoded by FM demodulation in demodulator 90 to obtain signal S_(A)′.This method therefore allows the transmission of different signalscarried at different frequencies, and has the advantage that the ONstate of switch 87 can be very short and the absorption very strongwithout inducing an increase in average consumption. In this way,feedback transmission is less sensitive to variation in the quality ofcoupling between the antennas 83 and 14.

In external control 10, the feedback signal F_(osc) is detected by thepickup 89 and fed to FM demodulator 90, which produces a voltage outputV_(OUT) that is proportional to F_(osc). V_(OUT) is fed to filter 91 andlevel detector 92 to obtain the information corresponding to theactuator signal S_(A), which in turn corresponds to the pulses appliedto the stepper motor coil. Microprocessor 80 counts these pulses tocalculate the corresponding displacement of the tension element 32,which is proportional to the number of pulses.

Signal V_(OUT) also is passed through analog-to-digital converter 93 andthe digital output is fed to the microprocessor 80, where signalprocessing is performed to detect perturbations of the shape of thefeedback signal that would indicate a blockage of the rotor of thestepper motor. Microprocessor 80 stops counting any detected motorpulses when it detects that the actuator is blocked, and outputs anindication of this status. Level detector 94 produces an output when itdetects that the demodulated signal V_(OUT) indicates the presence ofthe reference position signal S_(RP) due to activation of the referenceposition switch. This output induces a reset of the position of thetension element calculated by microprocessor 80 in the external control.In this way, a small imprecision, e.g. an offset, can be corrected.

As described above, external control 10 transmits both energy andcommands to the implantable controller circuitry in antenna/controllerpod 23. External control 10 also receives feedback information from theimplantable controller that can be correlated to the position of thetension element and the diameter of the ring. As will be apparent to oneof skill in the art, external control 10 and the implantable controllerare configured in a master-slave arrangement, in which the implantablecontroller is completely passive, awaiting both instructions and powerfrom external control 10.

Operational Modes

Referring to FIG. 19, some of the safety features of the system of thepresent invention are described. As discussed above with respect to FIG.18, both power and control signals are provided to the implantablecontroller from external control 10. Because power is delivered to theimplantable controller via magnetic induction, the amount of energydelivered to the controller depends on the quality of the couplingbetween external antenna 14 and the antenna circuitry contained withinantenna/controller pod 23.

The quality of the coupling may be evaluated by analyzing the level ofthe feedback signal received by external control 10, and a metriccorresponding to this parameter may be displayed on signal strengthindicator 17, which includes 6 LEDs (corresponding to six levels ofcoupling). If the coupling between the antennae is insufficient, themotor of actuator 35 may not work properly, resulting in an inaccurateadjustment of gastric band 21.

Accordingly, in a standard mode of operation, adjustment may be madeonly if the coupling quality is strong enough, as indicated by having atleast LED 5 or LED 6 in FIG. 19 illuminated. If, on the other hand, poorcoupling exists (e.g., one of the first four LEDs are illuminated) it isstill possible to perform some adjustment of the device, although theadjustment may be inaccurate.

The design of external control 10, in combination with patient microchipcard 16 (see FIG. 1), also ensures a high degree of efficacy and safety.First, as contemplated for use with gastric band 21 of the presentinvention, external control 10 is intended primarily for use by aphysician in an office or hospital setting, and not by the patientalone. Of course, in alternative embodiments, such as to treat urinaryor fecal incontinence, it would be essential to provide an externalcontrol for use by the patient. The simplicity of the design of theexternal control and ease of use would provide no impediment to use bythe patient for such embodiments.

As discussed with respect to FIG. 1, patient microchip card 16 stores,among other data, a serial number identifying a corresponding gastricband and the diameter of the ring upon completion of the previousadjustment. When the external control first transmits energy to theimplantable controller of the gastric band, the gastric band identifiesitself to the external control. In the standard mode of operation, theserial number stored on the patient microchip card must match thatreceived from the gastric band, otherwise no adjustment is permitted.

As a failsafe, however, the physician still may adjust the gastric bandeven if the patient has lost or misplaced his microchip card. In thiscase, the external control may be set in a “no card mode.” In this mode,the information displayed on display 13 of the exterior controlcorresponds only to the relative variation of the gastric band duringthat adjustment session, and is no longer indicative of absolutediameter. When the physician activates this mode, an emergency bit isset in the memory of the implantable controller to indicate the “no cardmode.” In subsequent adjustment sessions, the implantable controllerwill signal that the gastric band was adjusted in the “no card mode” andall further adjustments will be reported on a relative basis. If thepatient again locates the microchip card, the emergency bit may becleared by fully opening the gastric band and thus reaching thereference contact, which re-initializes the position. Subsequentadjustments will again be managed in the standard mode of operation.

During adjustment of the gastric ring physician places external antenna14 in a face-to-face position on the skin of the patient relative toantenna/controller pod 23 of the gastric ring, and to receive feedbackinformation from which the constricted diameter of the gastric ring maybe computed. In accordance with the principles of the present invention,it is possible to vary the diameter of the gastric ring without havingto undertake invasive surgical intervention, and this variation may becarried out at will, because multiple control cycles may be carried outat regular or irregular intervals, solely under the control of thetreating physician.

The gastric band system of the present invention is expected to beparticularly reliable, relative to previously-known hydraulic bands thatcan be adjusted by the patient, because only the physician typicallywill have access to the external control box needed to adjust the ring.For a ring embodiment intended for treatment of morbid obesity, thepatient therefore does not have free access to any means to adjust thediameter of the ring.

Moreover, because the gastric band of the present invention provides aprecise readout of the current diameter of the ring in the standard modeof operation, it may not be necessary for the patient to ingest aradiographic material (e.g., barium dye) to permit radiographicvisualization of the ring to confirm the adjusted size. The process ofadjusting the band accordingly may be carried out in a doctor's office,without the expense associated with radiographic confirmation of suchadjustments. In addition, the self-blocking configuration of the tensionelement and nut, in combination with the mechanical nature of thegastric band, overcome problems associated with previously-knownhydraulically-actuated gastric band systems.

Methods of Implantation and Removal

Referring now to FIG. 20, gastric band 21 of the present invention isshown implanted in a patient. Ring 22 is disposed encircling the upperportion of the patient's stomach S while antenna/controller pod 23 isdisposed adjacent to the patient's sternum ST. Pod 23 is located in thisposition beneath the patient's skin SK so that it is easily accessiblein the patient's chest area to facilitate coupling of the pod 23 toexternal antenna 14 of external control 10 (see FIG. 1).

Referring to FIGS. 21A to 21H, a method of implanting the gastric bandof the present invention is described. The method is similar tolaparoscopic procedures used to implant previously-knownhydraulically-actuated gastric bands. Access to the abdomen is obtainedby using 4 to 6 small holes, generally 10 to 18 mm in diameter, with atrocar inserted in each hole, as depicted in FIG. 21A. A camera andlaparoscopic surgical tools are introduced and manipulated through thetrocars. In addition, to permit free motion of the surgical tools andcamera, the abdomen is inflated with CO₂ to an overpressure ofapproximately 0.15 bars.

In FIGS. 21B-21E, the gastric band of the present invention isstraightened (as depicted in FIG. 8) and inserted, antenna first, intothe abdomen through an 18 mm trocar. Alternatively, a laparoscopiccannula may be used to make an incision and then withdrawn, and thedevice inserted through the opening so created (other instruments alsomay be used to form this laparotomy). In FIG. 21B, tag 25 ofantenna/controller pod 23 is shown entering the abdomen through trocar100 using atraumatic graspers 110. In FIG. 21C, housing 29 of thegastric ring is shown being drawn into the abdomen through trocar 100,again using atraumatic graspers 110. FIG. 21D shows ring 22 entering theabdomen in an extended position. In FIG. 21E, the ring is permitted toresume its preferred ring shape.

Ring 22 then is manipulated using atraumatic graspers 100 (as describedabove with respect to FIGS. 14A and 14B) to secure the gastric ringaround the upper portion of the patient's stomach until slot 73 of clip27 is engaged with flange 74, as shown in FIG. 21F. A fold of stomachtissue then may be sutured around the gastric ring to prevent migrationof the gastric band, as is typical for hydraulically-actuated gastricbands.

Finally, as shown in FIG. 21G, a channel may be formed through theabdominal wall and antenna/controller pod 23 passed through the channel.Tag 25 then is cut off of antenna/controller pod 23, and the pod issutured into position above the patient's sternum, as depicted in FIG.21H. The trocars then are removed, and the gastric band may be activatedto adjust the diameter of the ring as desired by the physician.

The process of removing the gastric ring of the present inventioninvolves substantially reversing the sequence of steps described above,and may be accomplished non-destructively. In particular, a plurality ofcannulae into the abdominal cavity and the abdominal cavity theninsufflated to create a pneumoperitoneum. Using laparoscopic graspers,the clip of the gastric ring may be unclipped and the elongated memberremoved from a position encircling the patient's stomach. The gastricring may then be straightened and withdrawn from the abdominal cavityeither through one of the plurality of cannulae or via a laparotomy.

Other Features

The gastric band of the present invention contains several airspaces asa result of its design, and applicants have observed that someprecautions are required when implanting the gastric band. Inparticular, airspaces within ring 22 typically contain air, which isapproximately 80% N₂, and much of the ring is encapsulated in a thinleak-proof silicone membrane (see FIGS. 2 and 4). Because this membranepermits CO₂ to diffuse into the ring about 20 times faster than theentrapped N₂ can diffuse out, significant swelling of the membrane mayresult when the gastric ring is inserted into an abdomen expanded withCO₂. Once the N₂ and CO₂ pressures equilibrate, the swelling resolves,typically in about three hours.

While the membrane is distended, however, there is a risk that themembrane may be pierced, for example, by the sharp needles employed tosuture the fold of stomach tissue over the ring, or to suture theantenna/controller pod in position. Applicants accordingly have devisedfour solutions to address this issue: (1) CO₂ preconditioning; (2) CO₂packaging; (3) a valve system; and (4) use of a less extensiblemembrane.

CO₂ preconditioning refers to placing the gastric band in a CO₂-filledcontainer for a specified duration, e.g., 3 hours, prior to implantationto permit the N₂ and CO₂ pressures to equilibrate prior to implantation.The gastric ring may be sealed within sterile packaging prior to suchpreconditioning. CO₂ packaging refers to packaging the gastric band inCO₂-filled container during the manufacturing process, so that nosubstantial swelling arises during the implantation procedure. Use of avalve system would entail implementing a pressure-relied valve on themembrane of the ring to avoid the build up of overpressure within thedevice, while preventing bodily fluids from ingressing into the device.Finally, the choice of a different membrane material or thickness may beused to control the swelling phenomena. During initial clinical testingof the device the preconditioning option is expected to be used,although CO₂ packaging is contemplated as the most expedient solutionfor commercial manufacture. Other gases than carbon dioxide may be usedto expand the abdomen, and such alternative preselected gases likewisemay be used to precondition the gastric ring of the present invention.

As stated in the Overview portion of the present application, thetelemetrically-powered and controlled ring system of the presentinvention has numerous applications apart from gastric banding for thetreatment of morbid obesity. For example, the ring system of the presentinvention may advantageously be used for the treatment of fecalincontinence, ileostomy, coleostomy, gastro-esophageal reflux disease,urinary incontinence and isolated-organ perfusion.

For treatment of fecal incontinence, the ring may be used with little orno modifications. In addition, because the ring adjustment procedurewill be performed by the patient on at least a daily basis, a portableuser-friendly external control may be used. In addition, because thering will regularly be transitioned between the closed and fully openedposition, the patient microchip card is unneeded. Instead, the fullyclosed position may be stored in the memory of the implantablecontroller, and read by the external remote at each use (subject toperiodic change by the physician).

A similarly modified device could be used by patients who have undergoneileostomy or coleostomy, or disposed surrounding the esophagealjunction, to treat gastro-esophageal reflux disease.

For treatment of urinary incontinence, the ring may be further modifiedto minimize the volume of the ring surrounding the urethra by moving theactuator motor to a location elsewhere in the lower abdomen or pelvis,and coupling the actuator to the motor via a transmission cable.

The present invention also may be beneficially employed to performisolated-organ perfusion. The treatment of certain cancers requiresexposure to levels of chemotherapy agents that are too high for systemiccirculation. It has been suggested that one solution to this problem isperform an open surgery procedure in which blood flow to the cancerousorgan is stopped and quiescient blood replaced by circulation from anexternal source containing a desired dose of drug. Individual ormultiple rings of the present invention may be used as valves to isolatethe cancerous organ and permit perfusion of the organ with high doses ofdrugs. Such procedures could thus be performed on a repetitive basiswithout surgery, thereby reducing the trauma and the risk to the patientwhile improving patient outcomes.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration. Further variations will beapparent to one skilled in the art in light of this disclosure and areintended to fall within the scope of the appended claims.

1. A method of laparoscopically implanting a gastric band comprising atelemetrically-driven mechanical actuator within a patient's abdominalcavity to control passage of food through the patient's stomach, themethod comprising: providing a gastric band comprising an elongatedmember having a flexible element defining a helical screw thread and atelemetrically-driven mechanical actuator that engages the helical screwthread to selectively constrict the elongated member against thepatient's stomach; inserting a plurality of cannulae into the abdominalcavity; insufflating of the abdominal cavity to create apneumoperitoneum; dissecting tissue surrounding the stomach to create apath for the elongated member using a first tool inserted into one ofthe cannulae; introducing the gastric band into the abdominal cavity;grasping the gastric band with a second tool placed through a cannula;and manipulating the elongated member to encircle the patient's stomachand form a stoma opening within the stomach.
 2. The method of claim 1wherein grasping the gastric band with a second tool placed through acannula comprises grasping the gastric band using laparoscopicinstruments.
 3. The method of claim 1 wherein manipulating the elongatedmember to encircle the patient's stomach comprises manipulating theelongated member using laparoscopic instruments.
 4. The method of claim1 wherein introducing the gastric band into the abdominal cavitycomprises introducing the gastric band via a laparoscopic cannula. 5.The method of claim 1 wherein introducing the gastric band into theabdominal cavity comprises introducing the gastric band via alaparotomy.
 6. The method of claim 1 further comprising preconditioningthe gastric band in a preselected gas.
 7. The method of claim 6, whereinthe preconditioning comprises placing the gastric band within acontainer having a preselected gas atmosphere for a sufficient durationso that the preselected gas diffuses into and replaces pre-existinggases located within the gastric band.
 8. The method of claim 7 whereinthe gastric band is sealed within sterile packaging prior topreconditioning.
 9. The method of claim 6 wherein preconditioning thegastric band comprises packaging the gastric band in a sealed containerhaving a preselected gas atmosphere.
 10. The method of claim 1 whereinthe gastric band further comprises an antenna coupled to thetelemetrically-driven mechanical actuator, the method further comprisingmanipulating the antenna using laparscopic instruments to locate theantenna subcutaneously atop the patient's sternum.
 11. The method ofclaim 10 further comprising suturing the antenna in position.
 12. Themethod of claim 1 wherein the elongated member comprises first andsecond ends and a clip disposed on the first end, wherein manipulatingthe elongated member to encircle the patient's stomach comprisesmanipulating the elongated member so that the clip engages the secondend.
 13. The method of claim 12 wherein the clip comprises an apertureconfigured to receive the second end, the method further comprisingmanipulating the second end of the elongated member to insert it throughthe clip.
 14. The method of claim 12 wherein the elongated memberfurther comprises a compressible ventral surface and a substantiallyrigid dorsal periphery, the method further comprising straightening theelongated member to permit passage into the abdominal cavity.
 15. Themethod of claim 12 further comprising: providing a remote control; andtelemetrically operating the telemetrically-driven actuator to confirmproper operation of the gastric band.
 16. The method of claim 15 whereintelemetrically operating the telemetrically-driven actuator comprisestransmitting power to the telemetrically-controlled actuator viaelectromagnetic induction.
 17. The method of claim 15 further comprisingassessing a coupling strength between the remote control and thetelemetrically-driven actuator.
 18. The method of claim 15 whereintelemetrically operating the telemetrically-driven actuator comprisesoperating the telemetrically-driven actuator to adjust a diameter of thestoma opening in fine increments.
 19. The method of claim 15 whereintelemetrically operating the telemetrically-driven actuator furthercomprises telemetrically operating the telemetrically-driven actuator sothat the remote control receives feedback indicating positional data forthe flexible element.
 20. The method of claim 1 wherein portions of thegastric band are different colors, wherein manipulating the elongatedmember to encircle the patient's stomach further comprises manipulatingselected portions of the gastric band in accordance with colors of theselected portions of the gastric band.
 21. A method of laparoscopicallyremoving a gastric ring comprising a telemetrically-driven mechanicalactuator from within a patient's abdominal cavity, the gastric ringincluding an elongated member having first and second ends and a clipdisposed on the first end that engages the second end, the methodcomprising: inserting a plurality of cannulae into the abdominal cavity;insufflating of the abdominal cavity to create a pneumoperitoneum;unclipping the clip from the second end of the elongated member;removing the elongated member from a position encircling the patient'sstomach; and removing the gastric ring from the patient's abdominalcavity.
 22. The method of claim 21 wherein unclipping the clip comprisesusing a laparoscopic instrument placed through a cannula to grasp thegastric ring.
 23. The method of claim 21 further comprisingstraightening the elongated member after removing the elongate memberfrom a position encircling the patient's stomach.
 24. The method ofclaim 21 wherein removing the gastric ring from the patient's abdominalcavity comprises withdrawing the gastric ring through one of theplurality of cannulae.
 25. The method of claim 21 wherein removing thegastric ring from the patient's abdominal cavity comprises withdrawingthe gastric ring through a laparotomy.
 26. A method of laparoscopicallyimplanting a gastric ring comprising a telemetrically-driven actuatorwithin a patient's abdominal cavity to control passage of food throughthe patient's stomach, the method comprising: providing a gastric ringcomprising an elongated member having first end and second ends, ahousing disposed on the second end of the elongated member, an electricmotor disposed within the housing, an actuator disposed within thehousing and coupled to the electric motor, a flexible element slidablydisposed within the elongated member, the flexible element defining ahelical screw thread that engages the actuator; placing at least onelaparoscopic cannula within the abdominal cavity; insufflating theabdominal cavity to create a pneumoperitoneum; placing at least twoadditional laparoscopic cannulae within the abdominal cavity; dissectingtissue surrounding the stomach to create a path for the gastric ring;introducing the gastric ring into the abdominal cavity; grasping thegastric ring with a tool placed through one of the cannulae; pulling thegastric ring into an encircling position around the stomach; andsecuring the gastric ring in the encircling position around the stomach.27. The method of claim 26 wherein grasping the gastric ring with a toolplaced through one of the cannulae comprises grasping the gastric ringusing a laparoscopic instrument.
 28. The method of claim 26 whereinpulling the elongated member to encircle the patient's stomach comprisesmanipulating the elongated member using laparoscopic instruments. 29.The method of claim 26 further comprising pre-conditioning the gastricring in a preselected gas atmosphere.
 30. The method of claim 29,wherein the preconditioning comprises placing the gastric ring within acontainer having a preselected gas atmosphere for a sufficient durationso that the preselected gas diffuses into and replaces pre-existinggases located within the gastric ring.
 31. The method of claim 30wherein the gastric ring is sealed within sterile packaging prior topreconditioning.
 32. The method of claim 30 wherein preconditioning thegastric ring comprises packaging the gastric ring in a sealed containerhaving a preselected gas atmosphere.
 33. The method of claim 26 whereinthe gastric ring further comprises an antenna coupled to the actuator,the method further comprising: manipulating the antenna usinglaparscopic instruments to locate the antenna subcutaneously atop thepatient's sternum.
 34. The method of claim 33 further comprisingsuturing the antenna in position.
 35. The method of claim 26 wherein theelongated member comprises a clip disposed on the first end, whereinsecuring the gastric ring in the encircling position around the stomachcomprises manipulating the elongated member so that the clip engages thesecond end.
 36. The method of claim 35 wherein the clip comprises anaperture configured to receive the second end, the method furthercomprising manipulating the second end of the elongated member to insertit through the clip.
 37. The method of claim 35 further comprisingstraightening the elongated member to permit passage through thelaparoscopic cannula into the abdominal cavity.
 38. The method of claim26 further comprising: providing a remote control; and telemetricallyoperating the actuator to confirm proper operation of the gastric ring.39. The method of claim 38 wherein telemetrically operating thetelemetrically-driven actuator comprises transmitting power to theactuator via electromagnetic induction.
 40. The method of claim 38further comprising assessing a coupling strength between the remotecontrol and the actuator.
 41. The method of claim 38 whereintelemetrically operating the actuator comprises operating the actuatorto adjust a length of the flexible element in predetermined increments.42. The method of claim 38 wherein telemetrically operating the actuatorfurther comprises receiving feedback indicating positional data for theflexible element.
 43. The method of claim 26 wherein portions of thegastric ring are different colors, wherein pulling the gastric ring intoan encircling position around the stomach further comprises manipulatingselected portions of the gastric ring in accordance with colors of theselected portions of the gastric ring.
 44. The method of claim 26wherein introducing the gastric ring into the abdominal cavity comprisesintroducing the gastric ring via a laparoscopic cannula.
 45. The methodof claim 26 wherein introducing the gastric ring into the abdominalcavity comprises introducing the gastric ring via a laparotomy.